The present invention relates generally to orthopedic prosthesis systems used in knee joint replacement surgeries and, more particularly, to a femoral implant for use in knee arthroplasty procedures.
The knee joint comprises the interface between the distal end of the femur and the proximal end of the tibia. In a properly-functioning knee joint, medial and lateral condyles of the femur pivot smoothly along menisci attached to respective medial and lateral condyles of the tibia. When the knee joint is damaged, the natural bones and cartilage that form the joint may be unable to properly articulate, which can lead to joint pain and, in some cases, interfere with normal use of the joint.
In some situations, surgery is required to restore normal use of the joint and reduce pain. Depending upon the severity of the damage, the surgery may involve partially or completely replacing the joint with prosthetic components. During such knee replacement procedures, a surgeon resects damaged portions of the bone and cartilage, while attempting to leave healthy tissue intact. The surgeon then fits the healthy tissue with artificial prosthetic components designed to replicate the resected tissue and restore proper knee joint operation.
One knee replacement procedure—total knee arthroplasty (“TKA”)—involves the resection of some or all of each of the medial and lateral condyles of both the femur and tibia and the removal of the fibro-cartilage menisci located at the femorotibial interface. A prosthetic femoral component, typically made of titanium or other strong, surgical-grade metal, is fitted and secured to the distal end of the femur to replace the resected portion of the femur. Similarly, a prosthetic tibial component, the base of which is also typically made of titanium or other suitable metal, is fitted and secured to the proximal end of the tibia to replace the resected portion of the tibia.
Femoral components commonly utilize a bone facing surface having a five-cut or five-surface baseline configuration, such as that depicted in FIGS. 2A-2C. These designs are typically not directed to patient-specific anatomy and use relatively basic lines and arcs for reduced cost manufacture. Designs of this type can be generally used on many patients having unique knee joint anatomies, and scaled only in size to accommodate the particular patient. Though advantageous for manufacture, the five basic cut design may require a high amount of bone volume to be removed in preparation to receive the implant thereon, thereby significantly reducing the strength of the bone.